At the request of the Department of Health of the Commonwealth of Puerto Rico, the Centers for Disease Control has investigated an outbreak of premature thelarche on the island. Dr. James Mills has been active as a consultant on this project. The most ambitious part of the CDC investigation, a case-control study of 130 matched pairs, has now been completed and the data have been analyzed. The CDC has now presented the Commonwealth of Puerto Rico Commission on Premature Thelarche with a final report based on the case-control study. Their findings are as follows: 1) they were not able to document that an epidemic has occurred, 2) they found no single agent which could account for all the observed cases, 3) they found suggestive evidence that exposure to soy-based formula, chicken, and family history (ovarian cyst in the mother) were important risk factors in girls under two years of age. Notably, they found no evidence that milk was an important etiologic agent. In summary the investigation failed to support allegations by pediatric endocrinologists that contaminated milk was responsible for the epidemic. They could not exclude the possibility that contaminated chicken may have caused some cases.